Bending machine



y 1966 H. VAN HARTEN 3,261,193

BENDING MACHINE Filed Sept. 10, 1964 ily/111111 A w INVENTOR HERBERT VAN HARTEN BY fl 'M $6 1 his A T TOPNEY United States Patent 3,261,193 BENDING MACHINE Herbert van Harten, Rodenkirehen, near Cologne, Germany, assignor to Hilgers Maschinenund Apparate- Bauanstalt m.b.H., Rodenkirchen, near Cologne, Germany File d Sept. 10, 1964, Ser. No. 395,528 Claims priority, application Germany, Sept. 10, 1963, H 50,232 Claims. (Cl. 72-150) The present invention relates to bending machines in general, and more particularly to improvements in pressure-die-type rotary bending machines. Still more particularly, the invention relates to improvements in the construction, mounting and manipulation of pressure dies in such bending machines.

It was found that a bend which is obtained by coldforming a tube or rod is often defective because the trailing portion of the stock is not guided properly by the pressure die. Thus, if the position of the pressure die with reference to the stock isnot selected with requisite precision, the material of the bend is often defective not only along the external surface but also as regards the wall thickness of a tube and other characteristics.

Accordingly, it is an important object of the present invention to provide an improved pressure-die-type rotary bending machine wherein the pressure die is constructed and mounted in such a way that it can be rapidly, accurately and readily adjusted to an infinite number of different positions so as to be in an optimum position to guide and control a tube or the like while the latter is deformed in response to rotation of the bending form and in response to pressure exerted by the customary clamping die which cooperates with the bending form.

Another object of the invention is to provide a bending machine of the just outlined characteristics wherein the pressure die may be readily removed to be replaced by a fresh pressure die or by a differently dimensioned pressure die so that the machine may be converted for shaping of differently dimensioned tubular or solid rod stock.

A futher object of the invention is to provide an improved slide for a pressure die and to construct and mount the slide in such a way that the pressure die may be adjusted not only with reference to but also together with the slide.

An additional object of the instant invention is to provide a composite carrier for a pressure die and to construct and assemble the carrier in such a way that the latter is adjustable with reference to the slide and that the pressured die may also be adjusted by changing the mutual positions of such components or sections which constitute the carrier.

Still another object of the invention is to provide a bending machine which embodies a pressure die of the above outlined characteristics and wherein the stock may be fed not only in response to rotation of the bending form but also independently of such rotation to prevent excessive longitudinal stresses in the material of the stock.

Briefly stated, the invention resides in the provision of a pressure-die-type bending machine, particularly for coldbending of elongated tubular workpieces. The machine comprises a main support preferably including a horizontal table, a bending form mounted on the table for rotation about a fixed vertical axis, a customary clamping die adjacent to and arranged to clamp the leading portion of an elongated horizontal workpiece against the peripheral surface of the form so that the workpiece is bent in response to rotation of the form, a pressure die arranged to engage a trailing portion of that workpiece whose leading portion is clamped against the form and to hold such -trailing portion against rotation with the form, a pressure ice slide which is preferably adjustable with reference to the table by being movable in grooves or similar guide means extending in the longitudinal direction of the unbent portion of the workpiece and which serves as a means for adjustably securing the pressure die to the table so that the pressure die may be adjusted with reference to the workpiece, and at least one adjusting device which enables an operator to change the position of the pressure die with reference to the pressure slide, i.e., with reference to the trailing portion of the workpiece, and to thus insure that the pressure die is in an optimum position relative to the workpiece and may properly engage the trailing portion during bending.

In accordance with a preferred embodiment of my invention, the pressure die is adjustable vertically, i.e., in directions parallel with the axis of the form. Additional adjustments may be effected by mounting the pressure die in such a way that it is adjustable about a horizontal axis which is substantially tangential to the curved peripheral surface of the bending form and/or by making the pressure die angularly adjustable about a vertical axis, preferably about the same axis along which the pressure die may be shifted between one or more higher and lower levels.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved bending machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic top plan view of a bending machine which embodies my invention;

FIG. 2 is an enlarged fragmentary transverse vertical section as seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 is a transverse vertical section as seen in the direction of arrows from the line III-III of FIG. 1.

Referring to the drawings, and first to FIG. 1, there is shown a pressure-die-type rotary bending machine for tube stock which comprises a main support including an elongated table 10. One end portion of the table 10 supports a head 11a which is rotatable about the fixed axis of a vertical shaft 15, and the head supports a bending form 11. FIG. 1 illustrates the form 11 in a position it assumes after rotating through an angle of approximately degrees, in a clockwise direction, whereby the leading portion 12a of an elongated tube 12 has been transformed into an arcuate bend. The form 11 cooperates with a clamping die 13 which is mounted on a clamping die slide 1301, and this slide is arranged to move in an arc whose center of curvature is located on the axis of the vertical shaft 15. The clamping die 13 is movable in strong frictional engagement with the adjacent portion of the tube 12 and shares the angular movement of the form 11 when the latter is rotated by a suitable motor and through a suitable transmission in a manner well known inthe art and not forming part of the present invention. In the starting position of the bending machine, the clamping die 13 is located immediately in front of an elongated pressure die 14 which is mounted in a manner as illustrated in FIG. 2. When the form 11 is rotated in a clockwise direction to move from the starting position to the position shown in FIG. 1, the clamping die 13 shares such angular movement and the pressure die 14 moves lengthwise in the axial direction of the undeformed horizontal trailing portion 12b of the tube 12. The curvature of the peripheral surface of the form 11 determines the extent to which the leading portion12aof the tube is deformed when the form is caused to rotate about the axis of the shaft 15. The clamping die 13 compels the trailing portion 12b of the tube to advance axially while the form 11 rotates, and the pressure die 14 takes the thrust of the free end of the tube and forces it to take the shape of the form as it rotates. The trailing portion 12b is tangential to the curved peripheral surface of the form 11.

The bending machine further comprises a device for feeding the tube lengthwise while the form 11 rotates, and this feeding device includes a hollow feed slide 16 which is reciprocable along elongated ways a on the top face of the table 10. The ways 10a are parallel to the trailing portion 12b of the tube and the feed slide 16 carries a fixed gripping jaw 17 which engages one side of the trailing portion 12b and cooperates with a reciprocable gripping jaw 18 engaging the other side of the trailing portion. The jaw 18 is reciprocable toward and away from the fixed jaw 17 by a mechanism which is accommodated in the interior of the feed slide 16 and which includes a double-acting hydraulic cylinder 1611, a piston 16b which is reciprocable in the cylinder, a piston rod 160 which is rigid with the piston and whose free end is connected to a system of links 16d, 162 by a horizontal pivot 16 The link 16:: is attached to the feed slide 16 by a pivot 16g, and the link 16d is attached to the jaw 18 by a third pivot 1612. The jaw 18 is guided by the feed slide 16 in such a way that it may reciprocate in a horizontal plane and in a direction at right angles to the axis of the trailing portion 12b. When the piston 16b is caused to move upwardly, the jaw 18 moves in a direction to the left, as viewed in FIG. 3, and grips the tube so that the latter is firmly held between the suitably configurated faces of the jaws 17, 18 and is compelled to move lengthwise in response to operation of a second hydraulic cylinder 16k whose piston rod 16m is connected to the feed slide 16. The force transmitted by the piston rod 16m to the feed slide 16 is preferably adjusta'ble .by means of suitable valves so that the pipe 12 may be advanced with a predetermined optimum force for a given type of bending operation.

In accordance with a feature of the present invention, the pressure die 14 is mounted on a pressure slide 19 which is adjustably secured to the table 10 in such a way that it may be moved in the transverse direction of the tube 12, depending on the radius of the form 11. This pressure slide is mounted on vertical fasteners in the form of bolts 20, 20a whose heads are received in T -grooves 10b or similar guide means provided in the top face of the table 10. Nuts 20b cooperate with the stems of the bolts 20, 20a to arrest the pressure slide 19 in a selected position of transverse adjustment with reference to the table 10.

That side of the slide 19 which is adjacent to the trailing portion 12b of the tube 12 is provided with a vertically extending trough-shaped recess 21, best shown in FIG. 2, which is bounded by a cylindrical surface and accommodates a cylindrical projection 22 of a carrier 23 whose vertical front face 23b is provided with a horizontally extending groove 23c to receive the rear portion of the pressure die 14. Thus, the pressure die 14 is slidable in the groove 23c, and the latter is normally parallel with the trailing portion 12b. The front face of the pressure die 14 is provided with a semispherical groove 29 to receive a portion of the tube. The projection 22 is formed with a vertically extending tapped bore 25 which receives a fulcrum here shown as a threaded spindle 24 having a non-circular head 24a so that it may be engaged and rotated by a suitable tool, not shown. The spindle 24 comprises a disk-shaped base 26 which extends into a complementary groove 27 provided in the underside of the slide 19. The base 26 rests on a detachable retaining plate 26'. The groove 27 is configurated in such a way that the base 26 is free to rotate but cannot move axially; therefore, the carrier 23 will move up or down whenever the operator decides to rotate the spindle 24 in a clockwise or counterclockwise direction. The spindle 24 serves as a self-locking adjusting device which regulates the distance between the pressure die 14 and the top face of the table 10, i.e., the-re is no need to lock the die 14 in a selected position of vertical adjustment because the die invariably remains in the selected position unless the operator decides to rotate the spindle. The axis of the spindle 24 coincides with the axis of the cylindrical surface surrounding the recess 21 and is parallel to the axis of the shaft 15.

In addition to being adjustable vertically (by means of the spindle 24) and transversely of the tube 12 (in response to loosening of the nuts 20b), the pressure die 14 is also rotatable within limits about the axis of the spindle 24 so that the operator may change the inclination of the groove 29 with reference to the axis of the trailing portion 12b. The means for adjusting the inclination of the pressure die 14 comprises a pair of threaded members or arresting screws 28 which are mounted at the opposite ends of the pressure slide 19 and whose tips engage the rear face of the carrier 23. Thus, merely 'by manipulating the arresting screws 28, which mesh with the slide 19, the operator may rapidly select an optimum angle between the tube 12 and pressure die 14 whereby the latter may but need not be parallel with the trailing portion 12b. The arresting screws 28 carry lock nuts 28a which serve to lock the pressure die 14 in a selected position of inclination. The carrier 23 resembles a two-armedv scale beam and is fulcrumed at 24.

In accordance with a further feature of my invention, the carrier 23 preferably comprises two sections including a rear section 23A and a front section 23B. These sections are respectively provided with concave and convex cylindrical faces 23a, 23d so that the front section 23B may be angularly adjusted about a horizontal axis which coincides with the axis of the groove 29, i.e., with the axis of the unbent portion of the tube 12. The sections 23A, 23B are held together by locking screws or bolts 23c whose heads abut against the front face of the section 23B and whose stems mesh with the section 23A. The section 23B is provided with vertical slots (not shown) which allow for at least some angular displacement of pressure die 14. Thus, the locking bolts 232 constitute means for facilitating angular adjustments of the pressure die 14 about an axis which normally coincides with the axis of the trailing portion 12b and is tangential to the arcuate peripheral surface of the form 11. The pressure die 14 is connected with the feed slide 16 by a helical spring 30 which returns it to the starting position.

It will be noted that the pressure die 14 is adjustable in a number of ways including adjustments with and with reference to the pressure slide 19. The adjustments which are shared by the slide 19 include adjustments in the transverse direction ofthe tube 12, and the remaining adjustments include adjustments in the axial direction of the Spindle 24, angular adjustments about the axis of the spindle 24, and angular adjustments about the axis of the tube 12, i.e., a total of as many as four adjustments which suflices to insure that the pressure die 14 may be placed in optimum position with reference to the tube stock.

If the wall of the tube is thin and the radius small, the bending machine may operate without any means which are normally utilized to prevent wrinkling of the inside of the bend and/ or collapse of the tube. However, when the diameter of the tube is rather large, I prefer to provide the bending machine with a suitable mandrel 31 and/or with a shoe of any suitable design, not forming part of the present invention.

The bending machine of my invention was subjected to extensive testing with different types of tubular and solid rod stock. It was found that proper adjustment of the pressure die with reference to the trailing portion of an elongated tube or solid bar invariably insures highly satisfactory bending of the stock. The machine may be used in connection with thin-walled tubes or pipes consisting of copper or another comparatively soft metallic material. Also, the machine is equally useful for further bending of preformed tubular or solid rod stock; in such instances, the adjustability of the pressure die plays an even more important role.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a pressure-die-type bending machine, particularly for cold-bending of elongated tubular workpieces, in combination, a main support; a bending form mounted on said main support for rotation about a fixed axis; a clamping die adjacent to and arranged to clamp a leading portion of a workpiece against said form so that the workpiece is bent in response to rotation of the form; a pressure die arranged to engage a trailing portion of the workpiece which is clamped by said form and to hold such trailing portion against rotation with the form; means for adjustably securing said pressure die to said main support so that the pressure die may be adjusted with reference to the workpiece; and means for adjusting said pressure die in directions parallel with said fixed axis.

2. In a pressure-die-type bending machine, particularly for cold-bending of elongated tubular workpieces, in combination, a main support; a bending form mounted on said main support for rotation about a fixed axis; a clamping die adjacent to and arranged to clamp a leading portion of a workpiece against said form so that the workpiece is bent in response to rotation of the form; a pressure die arranged to engage a trailing portion of the workpiece which is clamped by said form and to hold such trailing portion against rotation with the form; means for adjustably securing said pressure die to said main support so that the pressure die may be adjusted with reference to the workpiece; and means for angularly adjusting said pressure die about an axis which is normal to said fixed axis.

3. In a pressure-die-type bending machine, particularly for cold-bending of elongated tubular workpieces, in combination, a main support including a table; a form mounted on said table for rotation about a vertical axis; a clamping die mounted on said table adjacent to said form and arranged to clamp a leading portion of an elongated workpiece against said form so that the workpiece is bent in response to rotation of the form; a pressure slide mounted on said table and having a vertically extending recess; a carrier having a portion reciprocably received in said recess; means for adjusting said carrier in the longitudinal direction of said recess; and a pressure die mounted on said carrier and arranged to engage a trailing portion of the workpiece which is clamped by said clamping die so as to hold such trailing portion against rotation with said form.

4; In a pressure-die-type bending machine, particularly for cold-bending of elongated tubular workpieces, in combination, a main support including a horizontal table; a form mounted on said table for rotation about a vertical axis; a clamping die mounted on said table adjacent to said form, said clamping die being movable toward and away from said form so as to clamp the leading portion of an elongated horizontal workpiece which is supported by said table whereby the workpiece is bent in response to rotation of said form; elongated guide means provided on said table and extending substantially tangentially of said form; a slide longitudinally adjustably mounted on said guide means so as to be movable nearer to and away from said form, said slide having a vertical recess adjacent to 6 the trailing portion of that workpiece whose leading portion is clamped by said clamping die and said recess being bounded by a cylindrical surface; a carrier having a projection extending into and movable in the longitudinal direction of said recess, said projection having a tapped bore whose axis coincides with the axis of said cylindrical surface; a spindle having a lower portion rotatably mounted in said slide and a threaded stem extending through said bore and meshing with said projection so that, in response to rotation of said spindle, the carrier is moved vertically with reference to said slide; and a horizontal pressure die mounted on said carrier and arranged to engage the trailing portion of the workpiece which is clamped by said clamping die so as to hold such trailing portion against rotation with said form.

5. A structure as set forth in claim 4, wherein said carrier comprises a first section which is rigid with said projection and a second section which is connected with said pressure die, said second section being adjustable relative to said first section about a horizontal axis coinciding with the axis of the trailing portion of a workpiece which is engaged by said pressure die, and means for locking said second section in any of a plurality of positions of adjustment with reference to said first section.

6. A structure as set forth in claim 5, wherein one of said sections is provided with a convex cylindrical surface and the other section is provided with a concave cylindrical surface which abuts against said convex surface, the axes of said concave and convex surfaces coinciding with the axis of the trailing portion.

7. A structure as set forth in claim 6, wherein said second section is provided with elongated ways for said pressure die, said ways being parallel with the axes of said concave and convex cylindrical surfaces.

8. A structure as set forth in claim 5, wherein said carrier has limited freedom of rotation about said spindle and further comprising means for arresting said carrier in any one of a plurality of selected positions of angular adjustment with reference to said spindle.

9. A structure as set forth in claim 8, wherein said carrier comprises a pair of elongated arms which extend radially outwardly from said spindle and wherein the means for arresting said carrier comprises a pair of threaded members meshing with said slide and engaging the respective arms to hold the carrier in a selected position of adjustment, such position of adjustment being variable in response to rotation of said threaded members with reference to said slide.

10. In a bending machine, particularly in a pressure die-type machine for cold-bending of tubes and similar workpieces, in combination, a substantially horizontal table; a slide adjustably mounted on said table; a vertical spindle rotatably mounted on said pressure slide; a carrier meshing with said spindle so as to move vertically up or down when the spindle is rotated with reference thereto; and a pressure die mounted on said carrier.

11. In a bending machine, particularly in a pressuredie-type machine for cold-bending of tubes and similar workpieces, in combination, a substantially horizontal table; a slide adjustably mounted on said table; a vertical spindle rotatably mounted on said pressure slide; a carrier meshing with said spindle so as to move vertically up or down when the spindle is rotated with reference thereto, said carrier being rotatable within limits about said spindle into a plurality of different angular positions; means for arresting said carrier in any one of said angular positions; and a pressure die mounted on said carrier.

12. In a bending machine particularly in a pressuredie-type machine for cold-bending of tubes and similar workpieces, in combination, a substantially horizontal table; a slide adjustably mounted on said table; a vertical spindle rotatably mounted on said slide; a carrier comprising a first section meshing with said spindle so as to move vertically in response to rotation of the spindle, said carrier further comprising a second section which is angularly adjustable with reference to said first section about a horizontal axis; means for detachably locking said second section to said first section; and a pressure die secured to said second section.

13. In a bending machine, particularly in a pressuredie-type machine for cold-bending of tubes and similar workpieces, in combination, a substantially horizontal table having elongated horizontal guide means; a slide adjustably mounted in said guide means; a vertical spindle rotatably mounted on said pressure slide; a carrier meshing with said spindle so as to move vertically up or down when the spindle is rotated with reference thereto; and a. pressure die mounted on said carrier.

14. In a bending machine, particularly in a pressuredie-type machine for cold-bending of tubular stock, in combination, a substantially horizontal table; a slide mounted on said table; a pressure die having a substantially horizontal work-receiving groove; means for adjustably securing said die to said slide; and means for feeding the stock toward said pressure die.

15. In a bending machine, particularly in a pressuredie-type machine for cold-bending of tubes and similar 8 workpieces, in combination, a substantially horizontal table; a slide adjustably mounted on said table; a vertical spindle rotatably mounted on said pressure slide; a carrier meshing with said spindle so as to move vertically up or down when the spindle is rotated with reference thereto; a pressure die mounted on said carrier; a feed slide reciprocably mounted on said table and having work-engaging jaws; and means for moving said feed slide with reference to said table so as to feed a workpiece toward said pressure slide.

References Cited by the Examiner UNITED STATES PATENTS 1,007,834 11/1911 Wilson 72l50 1,662,428 3/1928 Lowe 72-150 FOREIGN PATENTS 1,154,180 9/1963 Germany.

CHARLES W. LANHAM, Primary Examiner.

R. D. GREFE, Assistant Examiner. 

1. IN A PRESSURE-DIE-TYPE BENDING MACHINE, PARTICULARLY FOR COLD-BENDING OF ELONGATED TUBULAR WORKPIECES, IN COMBINATION, A MAIN SUPPORT; A BENDING FORM MOUNTED ON SAID MAIN SUPPORT FOR ROTATION ABOUT A FIXED AXIS; A CLAMPING DIE ADJACENT TO AND ARRANGED TO CLAMP A LEADING PORTION OF A WORKPIECE AGAINST SAID FORM SO THAT THE WORKPIECE IS BENT IN RESPONSE TO ROTATION OF THE FORMS; A PRESSURE DIE ARRANGED TO ENGAGE A TRAILING PORTION OF THE WORKPIECE WHICH IS CLAMPED BY SAID FORM AND TO HOLD SUCH TRAILING PORTION AGAINST ROTATION WITH THE FORM; MEANS FOR ADJUSTABLY SECURING SAID PRESSURE DIE TO SAID MAIN SUPPORT SO THAT THE PRESSURE DIE MAY BE ADJUSTED WITH REFERENCE TO THE WORKPIECE; AND MEANS FOR ADJUSTING SAID PRESSURE DIE IN DIRECTIONS PARALLEL WITH SAID FIXED AXIS. 